2.3 Coasts - Hazards and Management

Depositional processes and features & opportunities of a coastline

Specification

Depositional processes 

Longshore drift – process by which beach material is transported along the coast by waves.

1. Waves approach beach at an angle controlled by prevailing winds
2. Material is moved up the beach at an angle in the swash
3. Material is carried directly down the beach in the backwash under gravity
4. The process repeats, moving material along the beach

Constructive waves – swash is stronger than backwash, resulting in more deposition

Depositional features

• Sand spit – a long, narrow stretch of sand and/or shingle, with one end attached to the mainland e.g Hel spit, Poland
• Sandbar – develops when a spit stretches across a bay linking two headlands. Behind the sandbar an area of water may be cut off from the sea to create a lagoon.
• Tombolo – forms when a beach or sand spit joins with an offshore island

Formation of a sand spit

1. Prevailing winds approach the coast at an angle 
2. Swash comes in at an angle, backwash is vertical
3. Material is transported in zig-zag manner – longshore drift
4. Sediment transported along the coast
5. Spit develops when there is a change in the coastline
6. Secondary winds result in hook formation

Case study – Mauritius 

• 322 km long coastline
• Surrounded by fringing coral reefs
• Coastal zones and lagoons are used mainly for:
  • Fishing – a source of income for locals, can be exported 
  • Leisure activities such as water skiing, diving, and sailing
  • Tourism:
    • There was a growth from 27,650 arrivals in 1970 to over 950,000 in 2013 -> One of the key reasons for Mauritius’ economic growth
• Mauritius also grew economically due to:
  • The establishment of industries and financial services 
  • A large increase in sugar export earnings

7-mark question example: ‘For a named area of coast you have studied, outline the opportunities  (+the associated hazards and their management)